Web browser-based email services are widely used for communicating information over the Internet. Besides the information in its message body, an email message often includes attachments of various document types. These attachments provide a recipient of the email message additional information in connection with the message body. For a long time, the recipient cannot access any content of an attachment without first downloading the attachment and then launching a native application program to open the attachment. On the other hand, a quick preview of even a slight portion of the content would be crucial for the recipient to determine what is covered by the attachment and whether it is worthwhile to download the attachment at all. Therefore, there is a need for systems and methods that enable email recipients to have a quick grasp of the contents of the email attachments without having to download anyone of them.